Fiber glass mat, method and laminate

ABSTRACT

A fiber glass mat containing a novolac resin having an acid solubility of at least about 35 wt. percent is especially useful for bonding to a light weight fibrous or foam web or board, such as a polymer fiber web. A method of making the mat by wet laying a slurry containing the fiber and the novolac resin particles and then further adding an aqueous solution or slurry containing a crosslinking agent for the novolac resin and a laminate containing the fiber glass mat are disclosed.

[0001] The present invention involves mats having particular use inbonding to fibrous webs and boards and to foam boards for uses such asin making automotive parts like headliners or topliners, lightweightstructural parts, and other laminates. The present invention alsoinvolves a method of making mats and laminates that contain one or morelayers of the inventive mat. The mats produced according to thisinvention are useful as reinforcement and dimensional stabilizers formaking a large number of inorganic, polymeric and/or natural fibrous weband foam laminate products.

BACKGROUND

[0002] It is known to use nonwoven fiber mats made with glass fibers andbonded with aqueous thermosetting resins, like urea formaldehyde orphenolic resole resins to make molded parts and laminates. It is alsoknown to use a nonwoven fiber glass mat to laminate to polymeric foamsuch as polystyrene foam to act as stiffeners and stabilizers in themanufacture of automotive parts such as automobile head liners, asdisclosed in U.S. Pat. No. 4,729,917. Products produced with foamlaminates having one or two layers of nonwoven fiber glass mat with ureaformaldehyde binder are affected by high humidity and high ambienttemperature to cause an unpleasant odor and also to deteriorate thebinder strength. Also, non-extendible mat, i. e. a mat bound with aresin binder that is fully cured, is relatively stiff and does notconform well to curves and complex curvature, such as three dimensionalcurvature, and still provide excellent rigidity or stiffness to the foamlaminate.

[0003] It is also known to make nonwoven fiber glass mats by choppingdry strands of glass fibers bound together with a binder to form choppedstrand, to collect the chopped strand on a moving conveyor in a randompattern, and to bond the chopped strand together at their crossings bydusting a dry, powdered thermoplastic binder like a polyamide, polyesteror ethylene vinyl acetate on wetted chopped strands followed by dryingand curing the binder, as disclosed in U.S. Pat. No. 5,565,049. Whilesuch mat products are very useful including bonding to a layer ofpolymeric foam to stiffen the foam, these mats do not have as high atensile strength as desired, and as achieved with a wet laid nonwovenfiber glass mat, because the bundles or chopped strands in the mat,according to the invention of the above cited patent, do not bondtogether as well as the individual fibers in a typical nonwoven mat.

[0004] For example, the average sum of the machine direction tensile andthe cross machine direction tensile for a chopped fiber glass strand matmade in this manner and having a basis weight of about 1.88 pounds per100 sq. ft. is about 24 lbs. per 3 inch width compared to at least twicethis tensile for wet laid nonwoven fiber glass mats. Mats made accordingto the above patented process also are more expensive to make than atypical nonwoven mat made with known wet laid processes.

[0005] It is also known to make a nonwoven fiber glass mat bonded with“B” staged acrylic resin having a glass transition temperature above 45degrees C. and to use such mats to form a laminate with a foam layer foruse in automotive head liners as disclosed in U.S. Pat. No. 6,008,147,but this mat is not well suited for laminating to a polymeric fibrousweb when the desired shape contains complex curvatures requiring the matto stretch substantially during molding. Further, it is known to use anacrylic copolymer latex, such as a self-crosslinking acrylic copolymerof an anionic emulsifying type as one component of at least a twocomponent binder for bonding glass fibers and particulate thermoplasticto make a glass fiber reinforced sheet that can later be hot molded intovarious shapes and articles, as disclosed in U.S. Pat. No. 5,393,379.

[0006] Finally, it is known to make stampable, moldable, sheets of fiberglass reinforced thermoplastic by forming a dilute aqueous slurrycontaining glass fibers and thermoplastic particles or thermosettingparticles smaller than 1 millimeter in size and passing the slurrythrough a moving forming screen to form the sheet and drying the sheetat a temperature high enough to bond the plastic particles togetherwhile retaining the particulate shape of the plastic particles, asdisclosed in European Patent Specification 148,760. A conventionalaqueous binder is applied to the wet formed mat of fibers and plasticparticles when a mat intended for cutting and press molding is made. Theadded aqueous binder provides the strength in the dry mat needed towithstand handling in the cutting and press molding operations.

[0007] European Patent Application 148,761 and U.S. Pat. No. 4,690,860also teach similar methods and mats as taught by European PatentSpecification 148,760. U.S. Pat. No. 4,690,860 teaches inpregnating astampable sheet containing glass fibers and a thermoplastic binder witha liquid thermosetting plastics material like liquid phenol formaldehydeor liquid melamine formaldehyde resin and then molding the sheet atelevated temperature and pressure to form a molded product that retainsits hardness over a wider range of temperatures. This reference alsosuggests using powdered thermosetting resins like those used for in-moldcoating of known art, but does not suggest forming a fibrous non-wovencontaining a novolac resin bonding the crossing fibers togetherthroughout the mat. Sheets or mats made according to these disclosuresare not sufficiently rigid or heat and sag, resistant for certainapplications like automotive headliners because they contain a 40-60percent of thermoplastic material and do not have a thermosetting matrixthroughout the mat.

SUMMARY OF THE INVENTION

[0008] The present invention includes a fibrous nonwoven mat forlaminating to other mats of the same or similar composition, to mats ofdifferent composition and to various other materials such as wood, apolymeric fiber web, fiber glass wool or mineral fiber webs or boards,foam boards, etc. comprising dispersed and crossing glass fibers boundtogether with a substantially melted Novolac resin having a solubilityin acetone of at least about 35 weight percent, preferably at leastabout 50% and most preferably at least about 70% to about 90 or 95percent such as about 85%, the Novolac resin preferably being a phenolicor epoxy Novolac resin. The mat also contains a crosslinking orhardening agent like hexamethylene tetramine. A Novalac resin as usedherein is a product of partially polymerized first stage phenol or epoxycontaining less than a stoichiometric amount of a crosslinking agentsuch as formaldehyde, amine, or other known crosslinking agent oragents. Novolac resins are well known in the art and normally areavailable as a powdered resin. Preferably the novolac resin is presentin the finished mat in amounts of 10-60 weight percent based on theweight of the dry mat, more preferably 45-55 wt. percent, and mostpreferably about 48-52 wt. percent. The novolac particles should be of asize range that allow all or most of the particles to become entrappedin the mat is the mat is being formed. When one inch long M glass fiberis used, the preferred particle size of the novolac is minus 40 mesh toplus 100 mesh (U.S. Std.).

[0009] The invention also includes a method of making the nonwoven matdescribed above comprising dispersing glass fibers and Novolac powder inan aqueous slurry, collecting the dispersed fibers onto a movingpermeable support to form a wet, fibrous, nonwoven mat, saturating thewet mat with an aqueous solution of slurry containing a crosslinking,hardening agent for the novolac resin, removing excess water andhardening agent from the wet, nonwoven mat and drying and heating themat in a temperature and time environment that will melt the Novolacpowder forming bonds where the fibers cross each other, but notthermoset the resulting Novolac resin bonds.

[0010] The present invention also includes molded laminates containingthe mat of the present invention on at least one surface of a polymeric,inorganic or natural fibrous web or board or foam core. The fibrous webpreferably can be a spun bonded, meltblown or a carded, lapped andneedled web of organic polymer or natural fiber.

[0011] The mats of the present invention preferably have bundles ofincompletely dispersed fibers in which the fibers are preferably atleast 0.75 inch long and most preferably at least 1 inch long. The matscan also contain pigments, dyes, flame retardants, and other additivesso long as they do not significantly reduce the ability of the mat tobond to a foam surface. The pigments or other additives can be includedin the fiber slurry, the aqueous crosslinking solution or can be sprayedor otherwise coated onto the mat later using known techniques.

DETAILED DESCRIPTION OF THE INVENTION

[0012] It is known to make reinforcing nonwoven mats from glass fibersand to use these mats as substrates in the manufacture of a large numberof roofing and other products. Any known method of making nonwoven matscan be used, such as the conventional wet laid processes described inU.S. Pat. Nos. 4,129,674, 4,112,174, 4,681,802, 4,810,576, and5,484,653, the disclosures of each being hereby incorporated herein byreference. In these processes a slurry of glass fiber is made by addingglass fiber to a typical white water in a pulper to disperse the fiberin the white water forming a slurry having a fiber concentration ofabout 0.2-1.0 weight percent, metering the slurry into a flow of whitewater to dilute the fiber concentration to about 0.1 wt. percent orbelow, and depositing this mixture onto a moving screen forming wire todewater and form a wet nonwoven fibrous mat. Usually an aqueous binderis then applied to the mat such as with a curtain coater and the excessbinder is removed by a vacuum knife and the resultant wet mat is driedin an oven which heats the mat to a temperature high enough to cure thebinder. This known process, with modifications as will be described, isused in the present invention. Alternative forming methods for makingthe mat include the use of well known paper or board making processessuch as cylinder forming, etc. and probably even “dry laying” usingcarding or random fiber distribution.

[0013] The preferred technique for the making of mats of the presentinvention is forming a dilute aqueous slurry of fibers and depositingthe slurry onto an inclined moving screen forming wire to dewater theslurry and form a wet nonwoven fibrous mat, on machines like aHydroformer™ manufactured by Voith—Sulzer of Appleton, Wis., or aDeltaformer™ manufactured by North County Engineers of Glenns Falls,N.Y.

[0014] The slurry used in the above mat forming process contains fibers,preferably glass fibers making up all or most of the fibers, and aNovolac powdered resin, preferably phenolic Novolac. The particle sizeshould be such that most to all of the particles will be entrapped inthe mat during forming and not be migrated or washed out of the mat withthe whitewater or aqueous crosslinking agent as these liquids flowthrough or out of the partially or fully formed mat.

[0015] The length and diameter of the glass fibers can be selected basedon the intended application and desired properties, but for use in theheadliner laminates disclosed herein, the preferred size of the glassfibers will be one inch long with an average fiber diameter of about 16microns. For headliner mat, at least some fibers longer than one inchmay prove to be better than one inch long. Any type of glass fiber canbe used, but E glass is most plentiful and is preferred for theheadliner application. Generally, the greater the fiber diameter and thelonger length of the fibers, the stiffer will be the resultant mat andvice versa.

[0016] It has been found that when the fibers selected for the mat areone inch long, and about sixteen micron diameter E glass fibers, thepreferred particle size of the Novolac is minus 40 mesh to plus 100 mesh(U.S. Standard screens) or about 149-420 microns. If the particles aremuch coarser than minus 40 mesh, they will tend to form lumps in or ontop of the mat, and if much finer than plus 100 mesh, insufficientNovolac powder will remain in the mat. Where shorter or smaller diameterfibers are used in substantial amounts, novolac particles smaller than149 microns can be used and accordingly, where longer or larger diameterfibers are used in substantial amounts, novolac particles larger than149 microns must be used and some particles larger than 420 microns canbe used.

[0017] Preferably, for a mat for an automotive headliner product, enoughNovolac particles are added to the whitewater slurry to produce a matcontaining about 45 weight percent Novolac resin in the finished drymat. The preferred phenolic powder is available from Georgia Pacific ofAtlanta, Ga., as 2026 Grade. Mats of the present invention preferablycontain about 10-60 weight percent novolac with about 45-55 wt. percentbeing preferred and about 48-52 wt. percent being most preferred.

[0018] Phenolic Novolac resins are described in a book entitled REINHOLDPLASTICS APPLICATIONS SERIES—PHENOLIC RESINS, by David F. Gould,published by Reinhold Publishing Corporation of New York, pages 31-33 asa crosslinking agent starved, insoluble, fusible resin made by usingless than a stoichiometric amount of crosslinking agent in thecondensing step, such as 0.9 mole of formaldehyde per 1 mole of phenolwhere the condensing step takes place in an acidic medium. Novolacresins are well known, are generally quite stable and are thermoplastic,but are generally too brittle to be of practical use and serve almostentirely as intermediates for the production of thermosetting resins.Novolac powders can be white, pink, yellow or tan in color. Propertiesof novolac resin include a melting point of about 85-95 degrees C., freephenol about 8-11 percent, and inclined plate flow of about 15-16millimeters.

[0019] Hexamethylene tetramine (HMT) is a known crosslinking, hardening,agent and is preferred, but other known hardening agents can be used.The HMT or other hardening agent is preferably added to the mat as anaqueous solution in a post addition to a wet web of fibers and novolacresin particles. Suitable additions of HMT to the mat as the mat entersthe oven include about 3-5 wt. percent based on the dry weight of themat or about 7-10 wt. percent based on the weight of novolac resin inthe mat. Greater amounts of hardening agent can be present, but isunecessary and increases the cost of the mat. If less than about 3percent is used, the novolac will not fully cure to a thermoset resinwhen the mat is molded under heat and pressure to form a laminate. TheHMT concentration in the solution can vary greatly, but concentrationsof 10, 15 and 25 wt. percents have been used successfully.

[0020] The wet nonwoven mat of glass fiber is then transferred to asecond moving screen and run through a saturating station, preferablyusing a conventional curtain coater, where an aqueous crosslinking agentis applied to the mat in any one of several known ways. The saturatedmat is then run over one or more suction knives in a known manner whilestill on the moving screen to remove excess aqueous crosslinking agentsolution. The preferred crosslinking agent for phenolic Novalac ishexamethylene tetramine, but other known crosslinking agents likeparaformaldehyde can also be used.

[0021] The wet mat is then transferred to a wire mesh moving oven beltor honeycomb drum and run through an oven to dry the wet mat and to meltthe Novolac powder sufficiently to flow into and around the places wherethe fibers contact and/or cross one another in close proximity to bondthe fibers together in the mat. When using phenolic Novolac powder, suchas Georgia Pacific Corporation's GP-2026, the preferred maximum oventemperature is about 149 degrees C.(300 degrees F.), but this can bevaried some as the time at temperature is varied to accomplish thedisclosed objective. It will be disclosed below that the mat can beheated to at least 350 degrees F. in the oven according to theinvention. The novolac in the finished dry mat should be mostly solublein acetone, indicating a very low level of crosslinking or cure, but notcompletely soluble. The most preferred novolac solubility of thepartially cured resin in the mat in acetone is at least about 70 wt.percent, such as about 85 wt. percent, but can be in the range of about35 to about 90 or 95 wt. percent. It is very important that the acetonesolubility of the mat be no less than about 35, preferably no less thanabout 50 wt. percent. The lower the acetone solubility, the lessflexible the mat for later molding, i. e. if too stiff, the mat won'tdrape or form complex curved shapes properly.

[0022] The majority of the fibers are glass fibers and preferably allthe fibers are glass fibers. The glass fibers should be at least 0.75inch long or longer, more preferably at least one inch long and can belonger such as about 1.25 or 1.5 inches long or longer. For other usesthan use disclosed in detail herein, the fibers can be shorter than 0.75inch. The glass fibers can have various fiber diameters dependent on thestrength and other properties desired in the mat as is well known, butsince the mat is intended to be relatively stiff, fibers having adiameter of at least 13 microns are preferred and at least 15 micron ismore preferred, such as M fiber which has an average fiber diameter ofabout 15.5-16.5 microns. It is preferred that the fibers be coated withan amino or ureido silane containing size composition which are wellknown and readily available from fiber glass manufacturers.

[0023] It is preferred that the length of the chopped strands of glassfiber be such that when the chopped strand is added to the wet matmachine in the stock preparation section the fiber does not completelydisperse, leaving some multi-fiber bundles in the stock. These bundles,much smaller in numbers of fibers and bundle size than the choppedstrand used in the prior art as discussed earlier, are beneficial to thestiffness of the present mat product and its stiffening performance whenlaminated to foam. This is accomplished in normal whitewater with afiber length of at least 1 inch and most preferably at least 1.25 inch.The skilled artisan will recognize that this can also be accomplishedwith shorter fiber by modifying the whitewater in known ways to reducedispersion effectiveness, reducing agitation and/or time in the pulperand the stock tank or a combination of these. The preferred fibers are Mor K 137 and K or M 117 E glass fibers available from Johns ManvilleInternational, Inc. of Denver, Co., but most a any commercially wet chopglass fiber product will be suitable. While the majority of the fibersare glass fibers, a minor portion of non-glass fibers can also be used,such as man made or natural organic fibers like Nylon™, polyester,polyethylene, polypropylene, cellulose or cellulose derivatives, etc.

[0024] The basis weight of the mat will depend upon the specificapplication. For stiffening polymeric fibrous webs for use in automotiveheadliners, the preferred basis weight of the dry mat for molding with apolyester fiber web to make automotive headliners is about 4.75 poundsper 100 square feet with the glass fibers constituting about 2.75 poundsper 100 square feet, but basis weights of about 2.25-4 pounds per 100square feet, particularly 2.25-3 pounds per 100 square feet, should alsobe suitable for this application and basis weights as low as 1.2 lbs.per 100 square feet are effective for greatly increasing the strengthand modulus of fiber glass wool boards and foam boards. The basis weightcan be decreased or increased, depending upon the desirable rigidity andstrength in the laminate. Basis weights as low as 0.5 pounds per 100square feet can be rolled up at the end of the mat machine and later cutand handled for use. The maximum weight would be determined by thecapability of the wet mat forming line and/or oven. Typically, for usein making laminates for automotive headliners, the glass fiber contentof the mat is in the range of 40-60 wt. percent, preferably 45-55 wt.percent and most preferably about 50 wt. percent.

[0025] The mats of the present invention may be hot molded alone as oneor more layers or hot molded in combination with other materials of allkinds suitable for molding. When the mats of the present invention areused on one or both surfaces of one or more layers of other material andhot molded, the resulting laminate will have a rigid surface with theremainder of the laminate having the properties of the other material ormaterials used. When the mats of the present invention are used as oneor more interior layers, the interior of the laminate will be rigid andthe surface or surfaces will have the properties of the other materialor materials used.

[0026] Hot molding is well known and it is also well known to preheatthe mats or laminate precursor sandwich to reduce molding time. When hotmolding mat of the present invention to a three dimensional shape, it ispreferred to first heat the inventive mat layer(s) to a temperaturesufficient to soften or melt the novolac resin in the mat beforedeforming to the desired shape, either in the mold or before enteringthe mold, then molding to the desired shape and further heating to asufficient temperature to react the hardening agent with the novolac tocrosslink and form a thermoset bond in the resin in the mat(s) of thelaminate. When a phenolic novolac is used in the mat a final temperatureof about 193 degrees C. (380 degrees F) for about 1 minute issatisfactory. Higher final temperatures will shorten the time requiredto reach complete cure, but can darken the novolac color if too high.

EXAMPLE 1

[0027] A fiber slurry was prepared by adding one inch long wet M 117 Etype glass wet chopped fiber from Johns Manville International, Inc. ofDenver, Co., having a silane containing chemical sizing on the surface,as is well known, to a known cationic white water containing Natrosol™thickening agent available from Aqualon, Inc. of Wilmington, Del., and acationic surfactant C-61, an ethoxylated tallow amine available fromCytec Industries, Inc. of Morristown, N.J., as a dispersing agent toform a fiber concentration of about 0.8 weight percent. Enough novolacpowdered resin, Grade 2026 from Georgia Pacific, was added to the slurryto produce a novolac content in the dry finished mat of 47.5 wt.percent. After allowing the slurry to agitate for about 5 minutes tothoroughly disperse the fibers, the slurry was metered into a movingstream of the same whitewater to dilute the fiber concentration to aconcentration averaging about 0.05 to 0.006 weight percent beforepumping the diluted slurry to a headbox of a Voith Hydroformer™ where awet nonwoven mat was continuously formed in sufficient basis weight toproduce a dry mat having a basis weight of about 4.4-⅘ pounds per 100square feet.

[0028] The wet mat was continuously removed from the forming wire andtransferred to an in-line Sandy Hill Curtain Coater where an aqueoussolution of hexamethylene tetramine was applied in excess and thesaturated mat was then run over a vacuum knife which removed the excessand left a sufficient quantity in the mat to produce a concentration ofhexamethylene tetramine in the dry mat of about 3.5 wt. percent.

[0029] The wet mat was then transferred to an oven belt and carriedthrough an oven to dry the mat and to heat the mat to a temperature ofabout 300 degrees F. for about 30 seconds to melt the resin binder,allowing it to flow into and around the fiber crossings to bond thefibers together.

[0030] The resultant mat had the following properties.

[0031] Thickness (mils)-69

[0032] Basis weight (lbs./100 sq. ft.)-4.7

[0033] Tensile Strength-Machine direction (lbs/3 in.)-34

[0034] Cross machine direction (lbs/3 in.)-31

[0035] Novolac solubility in acetone: 85 wt. percent

[0036] Mat emissions on curing at 193 degrees C. for 35 seconds(micrograms/gram of mat)

[0037] Phenol-69.4 Formaldehyde-18.5 Ammonia-15.4

[0038] Mat emissions on curing at 193 degrees C. for 60 seconds(micrograms/gram of mat)

[0039] Phenol-80 Formaldehyde-20.1 Ammonia-68.4

[0040] This mat was then placed on both sides of a web of dry laid,needled polyester fibers and this sandwich was then molded at about 193degrees C. and just enough pressure to deform the sandwich into theshape of the hot mold, and allowed to set under pressure and temperaturefor one minute. The resultant molded composite or laminate had astiffness much higher than prior art fiber glass mat and PET fiberlaminates and of chopped strand mat and PET fiber laminates molded inthe same manner as above. Under three point loading according to SAEMethod J 949, the strength of the laminate made with Example 1 mat, asdescribed above, withstood a peak force at failure of 20 Newtons,several Newtons higher than prior art headliner laminates. The strengthof the dry laid and needled polyester fibers in this test prior tolamination had negligible strength that was too low to measure.

EXAMPLE 2

[0041] This mat was made in the same manner as the mat in Example 1except that the wet mat, prior to saturation with HMT, contained, on adry basis, 49 wt. percent of the GP 2606 novolac resin particles, andthe wet mat entering the oven contained about 7 wt. percent HMT, basedon the amount of novolac resin, with the remainder being one inch M117glass fiber available from Johns Manville International, of Toledo,Ohio. The basis weight of the dried and partially cured mat was 6.7lbs/100 sq. ft. This mat had the following properties:

[0042] Machine direction tensile strength-60 lbs. per 3 in.

[0043] Cross machine direction tensile-60 lbs. per 3 in.

[0044] When this mat was laminated as described in Example 1, theresultant laminate had a stiffness about 2-3 times that of the prior artresole phenolformaldehyde bonded chopped strand mat and polyester fiberweb (described in Example 1) laminate.

EXAMPLES 3-5

[0045] These examples show the effect of different drying oventemperatures on the acetone solubility of the novolac resin in thepartially cured mats. These mats were made in the same manner describedin Example 1 except that the mat contained 47.5 wt. percent GP 2026resin and the basis weight of the mats ranged between 4.6 and 4.7lbs./100 sq. ft. Example 3 was dried and treated at 300 degrees F.,Example 4 at 325 degrees F. and Example 5 at 350 degrees F., all forabout 30 seconds, to produce a range of acetone solubilities in thepartially cured mats. The properties are shown in the following Table.TABLE Example 3 Example 4 Example 5 Basis weight 4.6 4.7 4.7 (lbs./100sq. ft.) Thickness (mils) 70 69 73 Machine Tensile (lbs/3 inch) 26 65140 Cross Machine Tensile (lbs/3 inch) 36 50 143 Acetone solubility (%wt. loss) 43.5 33.9 16.7

[0046] All of these mats could be subsequently molded in the methoddescribed in Example 1 and were suitable for making laminates of varioustypes including laminates for automotive headliners. However, mats withacetone solubility of less than about 35 wt. percent, based on theweight of the novolac resin in the mat, cannot be molded since thephenolic formaldehyde resin bonding the fibers together is cured toomuch to flow at high temperatures.

EXAMPLE 6

[0047] A mat was made using the procedure described in Example 1 exceptthat the novolac resin content was 25 wt. percent and a much lighterweight mat having a basis weight of 1.7 lbs./100 sq. ft. was produced.This mat was then laminated to two faces of a foam board and to a fiberglass wool board producing laminates having the following properties:Mat/Foam board Mat/FG wool board Peak strength (Newtons) 12.5 67 Modulusof Rupture (MPa) 530 3245

[0048] The modulus of rupture of the foam board itself was too low tomeasure. The strength of the FG wool board alone was 27 newtons and themodulus of rupture of the FG wool board alone was 328 MPa. Thus, evenrelatively light weight mats of the present invention producessubstantial strength improvement to light weight boards.

[0049] The mat and laminates of the present invention have furtheradvantages over the prior art products. These include a substantiallylower level of formaldehyde emissions during molding than when usingprior art mats bonded with resole resins like “B” staged phenolic resinand a lower cost compared to mats containing chopped strand to produceacceptable modulus of failure.

[0050] Numerous modifications can be made to the preferred embodimentdisclosed in the examples. One can modify the amount of novolac and thebasis weight to achieve the desired level of moldability and strength inthe molded laminate. Various known pigments, fillers, and other knownadditives can be incorporated into the mat by addition to either thewhitewater or to the aqueous crosslinking solution or slurry for thefunction they are known to provide.

[0051] When the word “about” is used herein it is meant that the amountor condition it modifies can vary some beyond that so long as theadvantages of the invention are realized. Practically, there is rarelythe time or resources available to very precisely determine the limitsof all the parameters of ones invention because to do would require aneffort far greater than can be justified at the time the invention isbeing developed to a commercial reality. The skilled artisan understandsthis and expects that the disclosed results of the invention mightextend, at least somewhat, beyond one or more of the limits disclosed.

[0052] Later, having the benefit of the inventors disclosure andunderstanding the inventive concept and embodiments disclosed includingthe best mode known to the inventor, the inventor and others can,without inventive effort, explore beyond the limits disclosed todetermine if the invention is realized beyond those limits and, whenembodiments are found to be without unexpected characteristics, thoseembodiments are within the meaning of the term about as used herein. Itis not difficult for the skilled artisan or others to determine whethersuch an embodiment is either as might be expected or, because of eithera break in the continuity of results or one or more features that aresignificantly better than reported by the inventor, is surprising andthus an unobvious teaching leading to a further advance in the art.

[0053] While the preferred embodiments of the invention have beendisclosed in detail, other embodiments within the described inventionand having other functional additives known or obvious to those skilledin the art are considered to be part of the present invention and areintended to be included in the invention claimed below.

I claim:
 1. A fiber mat comprising glass fibers bonded together at thelocations where the fibers cross each other with up to about 60 weightpercent, based on the dry weight of the mat, of novolac resin, saidresin having an acetone solubility of at least 35 wt. percent, and atleast about 3 weight percent hardening agent for said resin based on theweight of the mat, said hardening agent amounting to at least about 7weight percent of the weight of the novolac resin, said novolac resinbeing substantially in melted form bonding the fibers together.
 2. Themat of claim 1 wherein the hardening agent is hexamethylene tetramine(HMT).
 3. The mat of claim 1 wherein the glass fibers in the mat areabout one inch long and wherein the glass fibers make up about 90-40 wt.percent of the mat and the novolac resin makes up at least 10 wt.percent of the mat.
 4. The mat of claim 1 wherein said mat containsabout 45-55 wt. percent of novolac resin having a particle size of aboutminus 40 mesh and plus 100 mesh and the acetone solubility of the resinbinder is at least about 70 wt. percent.
 5. The mat of claim 2 whereinsaid mat contains about 45-55 wt. percent of novolac resin having aparticle size of about minus 40 mesh and plus 100 mesh and the acetonesolubility of the resin binder is at least about 70 wt. percent.
 6. Themat of claim 3 wherein said mat contains about 45-55 wt. percent ofnovolac resin having a particle size of about minus 40 mesh and plus 100mesh and the acetone solubility of the resin binder is at least about 70wt. percent.
 7. The mat of claim 1 wherein said mat contains about 48-52wt. percent of novolac resin having a particle size of about minus 40mesh to plus 100 mesh and the acetone solubility of the resin binder isat least about 85 wt. percent.
 8. A method of making a wet laid nonwovenmat bound with a novolac resin comprising the steps of: a) dispersingfibers and novolac resin particles in water to form a dilute slurry, b)flowing said slurry onto a moving first permeable belt to form a wetlayer of wet nonwoven fibers and resin particles, c) transferring saidwet layer off of said permeable belt onto a second moving permeablebelt, d) saturating said wet layer with an aqueous solution or slurrycontaining a crosslinking agent and removing excess slurry or solutionand excess crosslinking agent from said wet layer, e) transferring saidwet layer off of said second permeable belt onto an oven belt, and f)drying said wet layer to form a dry mat, the improvement comprising thatsaid resin is a novolac powder having an acetone solubility greater than95 wt. percent, that the aqueous solution or slurry contains a hardeningagent for the novolac, the amount of said resin and hardening agent inthe finished dried mat is at least 10-65 wt. percent, and said novolacresin is in contact with the hardening agent and is cured sufficientlyreduce the acetone solubility to between about 35 and about 95 weightpercent to give sufficient strength to the mat for handling and furtherprocessing, but not so much that the mat looses its ability to conformto a desired shape and bond to another mat or different material underheat and pressure.
 9. The method of claim 8 wherein the hardening agentis hexamethylene tetramine (HMT).
 10. The method of claim 8 wherein thefibers are glass fibers about one inch long, wherein the glass fibersmake up about 90-40 wt. percent of the mat and said wet layer on theoven belt contains about 7-10 wt. percent of a hardening agent, based onthe weight of novolac particles in said wet layer.
 11. The method ofclaim 10 wherein said finished mat contains about 45-55 wt. percent ofnovolac resin having an acetone solubility of at least 49 wt. percent.12. The method of claim 9 wherein said finished mat contains about 45-55wt. percent of novolac resin having an acetone solubility of at leastabout 49 wt. percent.
 13. A laminate having a core selected from a groupconsisting of foam board, a web of intermingled polymer fibers and afiber glass wool board with two opposed surfaces of the core beingbonded to a mat comprising glass fibers bonded together at the locationswhere the fibers cross each other with up to about 60 weight percent,based on the dry weight of the mat, of novolac resin, said resin havingan acetone solubility of at least 35 wt. percent, and at least about 3weight percent hardening agent for said resin based on the weight of themat, said hardening agent amounting to at least 7 weight percent of theweight of the novolac resin, said novolac resin being substantially inmelted form bonding the fibers together.
 14. The laminate of claim 13wherein the hardening agent is hexamethylene tetramine (HMT).
 15. Themat of claim 13 wherein the glass fibers in the mat are about one inchlong and wherein the glass fibers make up about 90-40 wt. percent of themat and the novolac resin makes up at least 10 wt. percent of the mat.16. The mat of claim 13 wherein said mat contains about 45-55 wt.percent of novolac resin having a particle size of about minus 40 meshand plus 100 mesh and the acetone solubility of the resin binder is atleast about 70 wt. percent.
 17. The mat of claim 14 wherein said matcontains about 45-55 wt. percent of novolac resin having a particle sizeof about minus 40 mesh and plus 100 mesh and the acetone solubility ofthe resin binder is at least about 70 wt. percent.
 18. The mat of claim15 wherein said mat contains about 45-55 wt. percent of novolac resinhaving a particle size of about minus 40 mesh and plus 100 mesh and theacetone solubility of the resin binder is at least about 70 wt. percent.19. The laminate described in claim 17 wherein the core is a web ofintermingled polymer fibers.
 20. The laminate described in claim 17wherein the core is a fiber glass wool board.
 21. The laminate describedin claim 17 wherein the core is a foam product.